Reactor for processing a semiconductor wafer

ABSTRACT

A method for processing a semiconductor wafer or similar article includes the step of spinning the wafer and applying a fluid to a first side of the wafer, while it is spinning. The fluid flows radially outwardly in all directions, over the first side of the wafer, via centrifugal force. As the fluid flows off of the circumferential edge of the wafer, it is contained in an annular reservoir, so that the fluid also flows onto an outer annular area of the second side of the wafer. An opening allows fluid to flow out of the reservoir. The opening defines the location of a parting line beyond which the fluid will not travel on the second side of the wafer. An apparatus for processing a semiconductor wafer or similar article includes a reactor having a processing chamber formed by upper and lower rotors. The wafer is supported between the rotors. The rotors are rotated by a spin motor. A processing fluid is introduced onto the top or bottom surface of the wafer, or onto both surfaces, at a central location. The fluid flows outwardly uniformly and in all directions. A wafer support automatically lifts the wafer, so that it can be removed from the reactor by a robot, when the rotors separate from each other after processing.

This application is a Continuation-In-Part of: International PatentApplication No. PCT/US99/05676, filed Mar. 15, 1999, and now pending;U.S. patent application Ser. No. 60/116,750 filed Jan. 22, 1999, and nowabandoned; U.S. patent application Ser. No. 09/113,435, filed Jul. 10,1998, and now U.S. Pat. No. 6,264,752; and U.S. patent application Ser.No. 09/041,901, filed Mar. 13, 1998, and now pending. Priority to theseapplications is claimed under 35 U.S.C. §§ 120 and 365.

BACKGROUND OF THE INVENTION

The semiconductor manufacturing industry is constantly seeking toimprove the processes used to manufacture microelectronic circuits andcomponents, such as the manufacture of integrated circuits from wafers.The improvements come in various forms but, generally, have one or moreobjectives as the desired goal. The objectives of many of these improvedprocesses include: 1) decreasing the amount of time required to processa wafer to form the desired integrated circuits; 2) increasing the yieldof usable integrated circuits per wafer by, for example, decreasing thelikelihood of contamination of the wafer during processing; 3) reducingthe number of steps required to turn a wafer into the desired integratedcircuits; and 4) reducing the cost of processing the wafers into thedesired integrated circuit by, for example, reducing the costsassociated with the chemicals required for the processing.

In the processing of wafers, it is often necessary to subject one ormore sides of the wafer to a fluid in either liquid, vapor or gaseousform. Such fluids are used to, for example, etch the wafer surface,clean the wafer surface, dry the wafer surface, passivate the wafersurface, deposit films on the wafer surface, etc. Control of thephysical parameters of the processing fluids, such as their temperature,molecular composition, dosing, etc., is often quite crucial to thesuccess of the processing operations. As such, the introduction of suchfluids to the surface of the wafer occurs in a controlled environment.Typically, such wafer processing occurs in what has commonly becomeknown as a reactor.

Various reactor constructions and configurations are known and used inthe industry. The Equinox reactor, manufactured by Semitool, Inc.,Kalispell, Mont., has a cup assembly that includes a fixed cupconstructed from a material that does not chemically react with theprocessing fluids that are to be used for the particular waferprocessing steps. Within the cup, a plurality of nozzles, or other meansfor introducing fluid into the cup, are provided. The fixed cup has anopen top portion. A rotor head assembly that supports the wafer is usedto seal the top of the cup to define a processing chamber in which thewafer is housed for processing. In addition to introducing the waferinto the processing chamber, the rotor head assembly may be used to spinthe wafer during introduction of the processing fluid onto the surfaceof the wafer, or after processing to thereby remove the processingfluid.

During processing, the wafer is presented to the rotor head assembly bya robotic device that operates in a substantially clean environment inwhich a number of processing reactors are present. The robotic devicepresents the wafer in an exposed state to the rotor head assembly in anorientation in which the side of the wafer that is to be processed isface up. The rotor head assembly inverts the wafer and engages and sealswith the cup for processing. As the wafer is processed, the wafer isoriented so that the side of the wafer being processed is face down.

However, it has now been recognized that demands for futuresemiconductor manufacturing processes may ultimately require morecontrol and economic efficiency from the reactor. As such, asubstantially new approach to processing and reactor design has beenundertaken, with the objective of providing greater control of the fluidprocesses currently used in connection with microelectronicmanufacturing, and to provide improved processes.

BRIEF SUMMARY OF THE INVENTION

An apparatus for processing a workplace in a micro-environment is setforth. Workpiece is defined as an object that at least comprises asubstrate, and may include further layers of material or manufacturedcomponents, such as one or more metallization levels, disposed on thesubstrate. The apparatus includes a rotor motor and a workpiece housing.The workpiece housing is connected to be rotated by the rotor motor. Theworkpiece housing further defines a processing chamber therein in whichone or more processing fluids are distributed across at least one faceof the workpiece by centrifugal force generated during rotation of thehousing.

Additionally, the reactor includes several advantageous mechanicalfeatures including those that allow the reactor to be used with roboticwafer transfer equipment, those that allow the reactor to be readilyre-configured for different processes, and those that allow theprocessing chamber of the reactor to be easily removed and serviced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a microelectronic workpiece housingand a rotor assembly constructed in accordance with one embodiment ofthe invention.

FIG. 2 is an exploded view of a further embodiment of a microelectronicworkpiece housing constructed in accordance with the teachings of thepresent invention.

FIG. 3 is a top plan view of the workpiece housing of FIG. 2 when thehousing is in an assembled state.

FIG. 4 is a cross-sectional view of the workpiece housing taken alongline IV—IV of FIG. 3.

FIG. 5 is a cross-sectional view of the workpiece housing taken alongline V—V of FIG. 3.

FIG. 6 is a cross-sectional view of the workpiece housing taken alongline VI—VI of FIG. 3.

FIGS. 7A and 7B are cross-sectional views showing the workpiece housingin a closed state and connected to a rotary drive assembly.

FIGS. 8A and 8B are cross-sectional views showing the workpiece housingin an open state and connected to a rotary drive assembly.

FIG. 9 illustrates one embodiment of an edge configuration thatfacilitates mutually exclusive processing of the upper and lower wafersurfaces in the workpiece housing.

FIG. 10 illustrates an embodiment of the workpiece housing employed inconnection with a self-pumping re-circulation system.

FIGS. 11 and 12 are schematic diagrams of exemplary processing toolsthat employ the present invention.

FIG. 13 illustrates a batch wafer processing tool constructed inaccordance with the principles of the present invention.

FIG. 14 illustrates a further embodiment of a reactor including featuresthat render it well-suited for integration with workpiece transferautomation equipment, wherein the reactor is in an open state forloading/unloading a workpiece that is to be processed.

FIG. 15 illustrates the embodiment of the reactor of FIG. 14 wherein thereactor is in a closed processing state.

FIG. 16 illustrates one embodiment of a biasing member that may be usedin the reactor of FIG. 14.

FIG. 17 illustrates a system in which the foregoing reactor is used toimplement a rinsing/drying process.

FIG. 18 is a cut-away, perspective view of another reactor embodiment.

FIG. 19 is a section view of the reactor shown in FIG. 18.

FIG. 20A is an enlarged detail of certain elements of the reactor ofFIG. 18.

FIG. 20B is a bottom perspective view of the lower processing chambershown in FIG. 19.

FIGS. 21 and 22 are further enlarged details of features shown in FIG.20.

FIG. 23 is an enlarged, perspective view of a rotor, as used in thereactor of FIG. 18.

FIG. 24 is an enlarged, perspective view of an alternative lower chamberembodiment.

FIGS. 25 and 26 are further enlarged details of one of the liftinglevers shown in FIG. 24.

FIGS. 27, 29 and 30 are section views of alternative edgeconfigurations.

FIG. 28 is a top view of the rotor shown in FIG. 27.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a cross-sectional view of one embodiment of a reactor, showngenerally at 10, constructed in accordance with the teachings of thepresent invention. The embodiment of the reactor 10 of FIG. 1 isgenerally comprised of a rotor portion 15 and a microelectronicworkpiece housing 20. The rotor portion 15 includes a plurality ofsupport members 25 that extend downwardly from the rotor portion 15 toengage the workpiece housing 20. Each of the support members 25 includesa groove 30 that is dimensioned to engage a radially extending flange 35that extends about a peripheral region of the workpiece housing 20.Rotor portion 15 further includes a rotor motor assembly 40 that isdisposed to rotate a hub portion 45, including the support members 25,about a central axis 47. Workpiece housing 20 is thus secured forco-rotation with hub portion 45 when support members 25 are engaged withflange 35. Other constructions of the rotor portion 15 and theengagement mechanism used for securement with the workpiece housing 20may also be used.

The workpiece housing 20 of the embodiment of FIG. 1 defines asubstantially closed processing chamber 50. Preferably, thesubstantially closed processing chamber 50 is formed in the generalshape of a semiconductor wafer or microelectronic workpiece 55 andclosely conforms with the surfaces of the workpiece. The specificconstruction of FIG. 1 includes an upper rotor or chamber member 60having an interior chamber face 65. The upper chamber member 60 includesa centrally disposed fluid inlet opening 70 in the interior chamber face65. The specific construction also includes a lower rotor or chambermember 75 having an interior chamber face 80. The lower chamber member75 has a centrally disposed fluid inlet opening 85 in the interiorchamber face 80. The upper chamber member 60 and the lower chambermember 75 engage one another to define the processing chamber 50. Theupper chamber member 60 includes sidewalls 90 that project downward fromthe interior chamber face 65. One or more outlets 100 are disposed atthe peripheral regions of the processing chamber 50 through thesidewalls 90 to allow fluid within the chamber 50 to exit therefromthrough centrifugal force that is generated when the housing 20 isrotated about axis 47.

In the illustrated embodiment, the microelectronic workpiece 55 is agenerally circular wafer having upper and lower planar surfaces. Assuch, the processing chamber 50 is generally circular in plan view andthe interior chamber faces 65 and 80 are generally planar and parallelto the upper and lower planar surfaces of the workpiece 55. The spacingbetween the interior chamber faces 65 and 80 and the upper and lowerplanar surfaces of the workpiece 55 is generally quite small. Suchspacing is preferably minimized to provide substantial control of thephysical properties of a processing fluid flowing through theinterstitial regions. In the embodiment shown, the spacing between thechamber faces and the workpiece upper and lower surfaces are about equalto the thickness of the wafer, e.g., 0.5-1.2 mm, and typically about 0.8mm.

The wafer 55 is spaced from the interior chamber face 80 by a pluralityof spacing members 105 extending from the interior chamber face 80.Preferably, a further set of spacing members 110 extend from theinterior chamber face 65 and are aligned with the spacing members 105 togrip the wafer 55 therebetween.

Fluid inlet openings 70 and 85 provide communication passageways throughwhich one or more processing fluids may enter the chamber 50 forprocessing the wafer surfaces. In the illustrated embodiment, processingfluids are delivered from above the wafer 55 to inlet 70 through a fluidsupply tube 115 having a fluid outlet nozzle 120 disposed proximateinlet 70. Fluid supply tube 115 extends centrally through the rotorportion 15 and is preferably concentric with the axis of rotation 47.Similarly, processing fluids are delivered from below the wafer 55 toinlet 85 through a fluid supply tube 125. Fluid supply tube 125terminates at a nozzle 130 disposed proximate inlet 85. Although nozzles120 and 130 terminate at a position that is spaced from their respectiveinlets, it will be recognized that tubes 115 and 125 may be extended sothat gaps are not present. Rather, nozzles 120 and 130 or tubes 115 and125 may include rotating seal members that abut and seal with therespective upper and lower chamber members 60 and 75 in the regions ofthe inlets 70 and 85. In such instances, care should be exercised in thedesign of the rotating joint so as to minimize any contaminationresulting from the wear of any moving component.

During processing, one or more processing fluids are individually orconcurrently supplied through fluid supply tubes 115 and 125 and inlets70 and 85 for contact with the surfaces of the workpiece 55 in thechamber 50. Preferably, the housing 20 is rotated about axis 47 by therotor portion 15 during processing to generate a continuous flow of anyfluid within the chamber 50 across the surfaces of the workpiece 55through the action of centripetal acceleration. Processing fluidentering the inlet openings 70 and 85 are thus driven across theworkpiece surfaces in a direction radially outward from the center ofthe workpiece 55 to the exterior perimeter of the workpiece 55. At theexterior perimeter of the workpiece 55, any spent processing fluid isdirected to exit the chamber 50 through outlets 100 as a result of thecentrifugal force. Spent processing fluids may be accumulated in a cupreservoir disposed below and/or about the workpiece housing 20. As willbe set forth below in an alternative embodiment, the peripheral regionsof the workpiece housing 20 may be constructed to effectively separatethe processing fluids provided through inlet 70 from the processingfluids supplied through inlet 85 so that opposite surfaces of wafer 55are processed using different processing fluids. In such an arrangement,the processing fluids may be separately accumulated at the peripheralregions of the housing 20 for disposal or re-circulation.

In the embodiment of FIG. 1, the workpiece housing 20 may constitute asingle wafer pod that may be used to transport the workpiece 55 betweenvarious processing stations and/or tools. If transport of the housing 20between the processing stations and/or tools takes place in a clean roomenvironment, the various openings of the housing 20 need not be sealed.However, if such transport is to take place in an environment in whichwafer contaminants are present, sealing of the various housing openingsshould be effected. For example, inlets 70 and 85 may each be providedwith respective polymer diaphragms having slits disposed therethrough.The ends of fluid supply tubes 115 and 125 in such instances may eachterminate in a tracor structure that may be used to extend through theslit of the respective diaphragm and introduce the processing fluid intothe chamber 50. Such tracor/slitted diaphragm constructions are used inthe medical industry in intravenous supply devices. Selection of thepolymer material used for the diaphragms should take into considerationthe particular processing fluids that will be introduced therethrough.Similar sealing of the outlets 100 may be undertaken in which the tracorstructures are inserted into the diaphragms once the housing 20 is in aclean room environment.

Alternatively, the outlets 100 themselves may be constructed to allowfluids from the processing chamber to exit therethrough while inhibitingthe ability of fluids to proceed from the exterior of housing 20 intochamber 50. This effect may be achieved, for example, by constructingthe openings 100 as nozzles in which the fluid flow opening has a largerdiameter at the interior of chamber 50 than the diameter of the openingat the exterior of the housing 20. In a further construction, arotational valve member may be used in conjunction with the plurality ofoutlets 100. The valve member, such as a ring with openingscorresponding to the position of outlets 100, would be disposedproximate the opening 100 and would be rotated to seal with the outlets100 during transport. The valve member would be rotated to a position inwhich outlets 100 are open during processing. Inert gas, such asnitrogen, can be injected into the chamber 50 through supply tubes 115and 125 immediately prior to transport of the housing to a subsequenttool or processing station. Various other mechanisms for sealing theoutlets 100 and inlets 70 and 85 may also be employed.

FIG. 2 is a perspective view of a further reactor construction whereinthe reactor is disposed at a fixed processing station and can open andclose to facilitate insertion and extraction of the workpiece. Thereactor, shown generally at 200, is comprised of separable upper andlower rotors or chamber members, 205 and 210, respectively. As in theprior embodiment, the upper chamber member 205 includes a generallyplanar chamber face 215 having a centrally disposed inlet 220. Althoughnot shown in the view of FIG. 2, the lower chamber member 210 likewisehas a generally planar interior chamber face 225 having a central inlet230 disposed therethrough. The upper chamber member 205 includes adownwardly extending sidewall 235 that, for example, may be formed froma sealing polymer material or may be formed integrally with otherportions of member 205.

The upper and lower chamber members, 205 and 210, are separable from oneanother to accept a workpiece therebetween. With a workpiece 55 disposedbetween them, the upper and lower rotors or chamber members, 205 and210, move toward one another to form a chamber in which the workpiece issupported in a position in which it is spaced from the planar interiorchamber faces 215 and 225. In the embodiment of the reactor disclosed inFIGS. 2-8B, the workpiece, such as a semiconductor wafer, is clamped inplace between a plurality of support members 240 and correspondingspacing members 255 when the upper and lower chamber members are joinedto form the chamber (see FIG. 7B). Axial movement of the upper and lowerchamber members toward and away from each other is facilitated by aplurality of fasteners 307, the construction of which will be describedin further detail below. Preferably, the plurality of fasteners 307 biasthe upper and lower chambers to a closed position such as illustrated atFIG. 7A.

In the disclosed embodiment, the plurality of wafer support members 240extend about a peripheral region of the upper chamber member 205 atpositions that are radially exterior of the sidewall 235. The wafersupport members 240 are preferably disposed for linear movement alongrespective axes 245 to allow the support members 240 to clamp the waferagainst the spacing members 255 when the upper and lower chamber membersare in a closed position (see FIG. 7A), and to allow the support members240 to release the wafer from such clamping action when the upper andlower chamber members are separated (see FIG. 8A). Each support member240 includes a support arm 250 that extends radially toward the centerof the upper chamber member 205. An end portion of each arm 250 overliesa corresponding spacing member 255 that extends from the interiorchamber face 215. Preferably, the spacing members 255 are each in theform of a cone having a vertex terminating proximate the end of thesupport arm 250. Notches 295 are disposed at peripheral portions of thelower chamber member 210 and engage rounded lower portions 300 of thewafer support members 240. When the lower chamber member 210 is urgedupward to the closed position, notches 295 engage end portions 300 ofthe support members 240 and drive them upward to secure the wafer 55between the arms 250 of the supports 240 and the corresponding spacingmembers 255. This closed state is illustrated in FIG. 5. In the closedposition, the notches 295 and corresponding notches 296 of the upperchamber member (see FIG. 2) provide a plurality of outlets at theperipheral regions of the reactor 200. Radial alignment of the arm 250of each support member 240 is maintained by a set pin 308 that extendsthrough lateral grooves 309 disposed through an upper portion of eachsupport member.

The construction of the fasteners 307 that allow the upper and lowerchamber members to be moved toward and away from one another isillustrated in FIGS. 2, 6 and 7B. As shown, the lower rotor or chambermember 210 includes a plurality of hollow cylinders 270 that are fixedthereto and extend upward through corresponding apertures 275 at theperipheral region of the upper rotor or chamber member 205 to form lowerportions of each fastener 307. Rods 280 extend into the hollow of thecylinders 270 and are secured to form an upper portion of each fastener307. Together, the rods 280 and cylinders 270 form the fasteners 307that allow relative linear movement between the upper and lower chambermembers, 205 and 210, along axis 283 between the open and closedposition. Two flanges, 285 and 290, are disposed at an upper portion ofeach rod 280. Flange 285 functions as a stop member that limits theextent of separation between the upper and lower chamber members, 205and 210, in the open position. Flanges 290 provide a surface againstwhich a biasing member, such as a spring (see FIG. 6) or the like, actsto bias the upper and lower chamber members, 205 and 210, to the closedposition.

With reference to FIG. 6, the spring 303 or the like, has a first endthat is positioned within a circular groove 305 that extends about eachrespective fastener 307. A second end of each spring is disposed toengage flange 290 of the respective fastener 307 in a compressed statethereby causing the spring to generate a force that drives the fastener307 and the lower chamber member 210 upward into engagement with theupper chamber member 205.

The reactor 200 is designed to be rotated about a central axis duringprocessing of the workpiece. To this end, a centrally disposed shaft 260extends from an upper portion of the upper chamber member 205. As willbe illustrated in further detail below in FIGS. 7A-8B, the shaft 260 isconnected to engage a rotary drive motor for rotational drive of thereactor 200. The shaft 260 is constructed to have a centrally disposedfluid passageway (see FIG. 4) through which a processing fluid may beprovided to inlet 220. Alternatively, the central passageway mayfunction as a conduit for a separate fluid inlet tube or the like.

As illustrated in FIGS. 3 and 4, a plurality of optional overflowpassageways 312 extend radially from a central portion of the upperchamber member 205. Shaft 260 terminates in a flared end portion 315having inlet notches 320 that provide fluid communication between theupper portion of processing chamber 310 and the overflow passageways312. The flared end 315 of the shaft 260 is secured with the upperchamber member 205 with, for example, a mounting plate 325. Mountingplate 325, in turn, is secured to the upper chamber member 205 with aplurality of fasteners 330 (FIG. 5). Overflow passages 312 allowprocessing fluid to exit the chamber 310 when the flow of fluid to thechamber 310 exceeds the fluid flow from the peripheral outlets of thechamber.

FIGS. 7A and 7B are cross-sectional views showing the reactor 200 in aclosed state and connected to a rotary drive assembly, shown generallyat 400, while FIGS. 8A and 8B are similar cross-sectional views showingthe reactor 200 in an opened state. As shown, shaft 260 extends upwardinto the rotary drive assembly 400. Shaft 260 is provided with thecomponents necessary to cooperate with a stator 405 to form a rotarydrive motor assembly 410.

As in the embodiment of FIG. 1, the upper and lower chamber members 205and 210 join to define the substantially closed processing chamber 310that, in the preferred embodiment, substantially conforms to the shapeof the workpiece 55. Preferably, the wafer 55 is supported within thechamber 310 in a position in which its upper and lower faces are spacedfrom the interior chamber faces 215 and 225. As described above, suchsupport is facilitated by the support members 240 and the spacingmembers 255 that clamp the peripheral edges of the wafer 55 therebetweenwhen the reactor 200 is in the closed position of FIGS. 7A and 7B.

It is in the closed state of FIGS. 7A and 7B that processing of thewafer 55 takes place. With the wafer secured within the processingchamber 310, processing fluid is provided through passageway 415 ofshaft 260 and inlet 220 into the interior of chamber 310. Similarly,processing fluid is also provided to the chamber 310 through aprocessing supply tube 125 that directs fluid flow through inlet 230. Asthe reactor 200 is rotated by the rotary drive motor assembly 410, anyprocessing fluid supplied through inlets 220 and 230 is driven acrossthe surfaces of the wafer 55 by forces generated through centrifugalforce. Spent processing fluid exits the processing chamber 310 from theoutlets at the peripheral regions of the reactor 200 formed by notches295 and 296. Such outlets exist since the support members 240 are notconstructed to significantly obstruct the resulting fluid flow.Alternatively, or in addition, further outlets may be provided at theperipheral regions.

Once processing has been completed, the reactor 200 is opened to allowaccess to the wafer, such as shown in FIGS. 8A and 8B. After processing,actuator 425 is used to drive an actuating ring 430 downward intoengagement with upper portions of the fasteners 307. Fasteners 307 aredriven against the bias of spring 303 causing the lower chamber member210 to descend and separate from the upper chamber member 205. As thelower chamber member 210 is lowered, the support members 240 follow itunder the influence of gravity, or against the influence of a biasingmember, while concurrently lowering the wafer 55. In the lower position,the reactor chamber 310 is opened thereby exposing the wafer 55 forremoval and/or allowing a new wafer to be inserted into the reactor 200.Such insertion and extraction can take place either manually, or by anautomatic robot.

The foregoing arrangement makes the reactor 200 particularly well-suitedfor automated workpiece loading and unloading by, for example, a robotictransfer mechanism or the like. As evident from a comparison of FIGS. 7Aand 8A, the spacing between the upper surface of the workpiece and theinterior chamber wall of the upper chamber member 205 varies dependingon whether the reactor 200 is in an open or closed state. When in theopen state, the upper surface of the workpiece is spaced from theinterior chamber wall of the upper chamber member 205 by a distance, x1,that provides sufficient clearance for operation of, for example, aworkpiece transfer arm of a robotic transfer mechanism. When in theclosed processing state, the upper surface of the workpiece is spacedfrom the interior chamber wall of the upper chamber member 205 by adistance, x2, that is less than the distance, x1. The distance, x2, inthe disclosed embodiment may be chosen to correspond to the spacing thatis desired during workpiece processing operations.

FIG. 9 illustrates an edge configuration that facilitates separateprocessing of each side of the wafer 55. As illustrated, a dividingmember 500 extends from the sidewall 235 of the processing chamber 310to a position immediately proximate the peripheral edge 505 of the wafer55. The dividing member 500 may take on a variety of shapes, theillustrated tapered shape being merely one configuration. The dividingmember 500 preferably extends about the entire circumference of thechamber 310. A first set of one or more outlets 510 is disposed abovethe dividing member 500 to receive spent processing fluid from the uppersurface of the wafer 55. Similarly, a second set of one or more outlets515 is disposed below the dividing member 500 to receive spentprocessing fluid from the lower surface of the wafer 55. When the wafer55 rotates during processing, the fluid through supply 415 is providedto the upper surface of the wafer 55 and spreads across the surfacethrough the action of centrifugal force. Similarly, the fluid fromsupply tube 125 is provided to the lower surface of the wafer 55 andspreads across the surface through the action of centripetalacceleration. Because the edge of the dividing member 500 is so close tothe peripheral edge of the wafer 55, processing fluid from the uppersurface of the wafer 55 does not proceed below the dividing member 500,and processing fluid from the lower surface of the wafer 55 does notproceed above the dividing member 500. As such, this reactorconstruction makes it possible to concurrently process both the upperand lower surfaces of the wafer 55 in a mutually exclusive manner usingdifferent processing fluids and steps.

FIG. 9 also illustrates one manner in which the processing fluidssupplied to the upper and lower wafer surfaces may be collected in amutually exclusive manner. As shown, a fluid collector 520 is disposedabout the exterior periphery of the reactor 200. The fluid collector 520includes a first collection region 525 having a splatter stop 530 and afluid trench 535 that is structured to guide fluid flung from theoutlets 510 to a first drain 540 where the spent fluid from the upperwafer surface may be directed to a collection reservoir for disposal orre-circulation. The fluid collector 520 further includes a secondcollection region 550 having a further splatter stop 555 and a furtherfluid trench 560 that is structured to guide fluid flung from theoutlets 515 to a second drain 565 where the spent fluid from the lowerwafer surface may be directed to a collection reservoir for disposal orre-circulation.

FIG. 10 illustrates an embodiment of the reactor 200 having an alternateconfiguration for supplying processing fluid through the fluid inletopening 230. As shown, the workpiece housing 20 is disposed in a cup570. The cup 570 includes sidewalls 575 exterior to the outlets 100 tocollect fluid as it exits the chamber 310. An angled bottom surface 580directs the collected fluid to a sump 585. Fluid supply line 587 isconnected to provide an amount of fluid to the sump 585. The sump 585 isalso preferably provided with a drain valve 589. An inlet stem 592defines a channel 595 that includes a first end having an opening 597that opens to the sump 585 at one end thereof and a second end thatopens to the inlet opening 230.

The operation of the embodiment shown in FIG. 10, processing fluid isprovided through supply line 587 to the sump 585 while the reactor 200is spinning. Once the sump 585 is full, the fluid flow to the sumpthrough supply line 587 is eliminated. Centrifugal force resulting fromthe spinning of the reactor 200 provides a pressure differential thatdrives the fluid through openings 597 and 230, into chamber 310 tocontact at least the lower surface of the wafer 55, and exit outlets 100where the fluid is re-circulated to the sump 585 for further use.

There are numerous advantages to the self-pumping re-circulation systemillustrated in FIG. 10. The tight fluid loop minimizes lags in processparameter control thereby making it easier to control such physicalparameters as fluid temperature, fluid flow, etc.. Further, there is noheat loss to plumbing, tank walls, pumps, etc.. Still further, thesystem does not use a separate pump, thereby eliminating pump failureswhich are common when pumping hot, aggressive chemistries.

FIGS. 11 and 12 illustrate two different types of processing tools, eachof which may employ one or more processing stations including thereactor constructions described above. FIG. 11 is a schematic blockdiagram of a tool, shown generally at 600, including a plurality ofprocessing stations 605 disposed about an arcuate path 606. Theprocessing stations 605 may all perform similar processing operations onthe wafer, or may perform different but complementary processingoperations. For example, one or more of the processing stations 605 mayexecute an electrodeposition process of a metal, such as copper, on thewafer, while one or more of the other processing stations performcomplementary processes such as, for example, clean/dry processing,pre-wetting processes, photoresist processes, etc.

Wafers that are to be processed are supplied to the tool 600 at aninput/output station 607. The wafers may be supplied to the tool 600 in,for example, S.M.I.F. pods, each having a plurality of the wafersdisposed therein. Alternatively, the wafers may be presented to the tool600 in individual workpiece housings, such as at 20 of FIG. 1.

Each of the processing stations 605 may be accessed by a robotic arm610. The robotic arm 610 transports the workpiece housings, orindividual wafers, to and from the input/output station 607. The roboticarm 610 also transports the wafers or housings between the variousprocessing stations 605.

In the embodiment of FIG. 11, the robotic arm 610 rotates about axis 615to perform the transport operations along path 606. In contrast, thetool shown generally at 620 of the FIG. 12 utilizes one or more roboticarms 625 that travel along a linear path 630 to perform the requiredtransport operations. As in the embodiment of FIG. 10, a plurality ofindividual processing stations 605 are used, but more processingstations 605 may be provided in a single processing tool in thisarrangement.

FIG. 13 illustrates one maimer of employing a plurality of workpiecehousings 700, such as those described above, in a batch processingapparatus 702. As shown, the workpiece housings 700 are stackedvertically with respect to one another and are attached for rotation bya common rotor motor 704 about a common rotation axis 706. The apparatus702 further includes a process fluid delivery system 708. The deliverysystem 708 includes a stationary manifold 710 that accepts processingfluid from a fluid supply (not shown). The stationary manifold 710 hasan outlet end connected to the input of a rotating manifold 712. Therotating manifold 712 is secured for co-rotation with the housings 700and, therefore, is connected to the stationary manifold 710 at arotating joint 714. A plurality of fluid supply lines 716 extend fromthe rotating manifold 712 and terminate at respective nozzle portions718 proximate inlets of the housings 700. Nozzle portions 718 that aredisposed between two housings 700 are constructed to provide fluidstreams that are directed in both the upward and downward directions. Incontrast, the lowermost supply line 716 includes a nozzle portion 718that directs a fluid stream only in the upward direction. The uppermostportion of the rotating manifold 712 includes an outlet 720 thatprovides processing fluid to the fluid inlet of the uppermost housing700.

The batch processing apparatus 702 of FIG. 13 is constructed toconcurrently supply the same fluid to both the upper and lower inlets ofeach housing 700. However, other configurations may also be employed.For example, nozzle portions 718 may include valve members thatselectively open and close depending on whether the fluid is to besupplied through the upper and/or lower inlets of each housing 700. Insuch instances, it may be desirable to employ an edge configuration,such as the one shown in FIG. 9, in each of the housings 700 to provideisolation of the fluids supplied to the upper and lower surfaces of thewafers 55. Still further, the apparatus 702 may include concentricmanifolds for supplying two different fluids concurrently to individualsupply lines respectively associated with the upper and lower inlets ofthe housings 700.

An embodiment of the reactor that is particularly well-suited forintegration in an automated processing tool is illustrated in FIG. 14.The reactor, shown generally at 800, includes features that cooperate ina unique manner to allow a robotic arm or the like to insert and extracta workpiece to and from the reactor 800 during loading and unloadingoperations while also maintaining relatively tight clearances betweenthe workpiece and the interior chamber walls of the reactor duringprocessing.

One of the principal differences between the reactor embodimentsdescribed above and the reactor 800 of FIG. 14 lies in the nature of theworkpiece support assembly. As shown, reactor 800 includes a workpiecesupport assembly associated with the lower chamber member 210. Theworkpiece support assembly includes a plurality of workpiece supportmembers 810 that extend through the lower chamber member 210. Theworkpiece support members 810 are supported at a lower end thereof by abiasing member 815. At the upper end of each, the workpiece supportmember 810 has a workpiece support surface 820 and a guide structure825. Referring to FIG. 15, the guide structure 825 extends from theworkpiece support surface 820 and terminates at a frustoconical section830. The guide structure 825 assists in urging the peripheral edges ofthe workpiece into proper alignment with the workpiece support surface820 thereby ensuring proper registration of the workpiece duringprocessing. The guide structure 825 may also serve as a spacer thatdefines the clearance between the interior chamber wall of the upperchamber member 205 and the upper surface of the workpiece.

The biasing member 815 of the illustrated embodiment serves to bias theworkpiece support members 810 in an upward direction when the upper andlower chamber members 205 and 210 are in the illustrated open conditionin which the reactor 800 is ready for loading or unloading theworkpiece. The biasing member 815 may take on various forms. Forexample, a single biasing structure may be used that is common to all ofthe workpiece support members 810. Alternatively, as shown in thedisclosed embodiment, individual biasing structures may be respectivelyassociated with individual ones of the workpiece support members 810.The individual biasing structures are in the form of leaf springs 835but, for example, may alternatively be in the form of coil springactuators or the like.

As in the embodiment of the reactor described above, the upper and lowerchamber members 205 and 210 of reactor 800 are movable with respect toone another between the open condition of FIG. 14 to a closed processingcondition as illustrated in FIG. 15. As the chamber members 205 and 210move toward one another, the frustoconical sections 830 of the workpiecesupport members 810 engage the interior chamber wall of the upperchamber member 205. Continued movement between the chamber members 205and 210 drives the workpiece support members 810 against the leafsprings 835 until the workpiece is clamped between the support surfaces820 of the workpiece support members 810 and corresponding projections840 that extend from the interior chamber wall of the upper chambermember 205. While in this closed state, the reactor is ready to processthe workpiece.

The reactor 800 of FIG. 14 also includes structures which assists inensuring proper registration between the upper and a lower chambermembers 210 and 205 as they are brought proximate one another to theirprocessing position. In the illustrated embodiment, these structures arein the form of lead-in pins 845 that extend from one of the chambermembers to engage corresponding apertures of the other of the chambermembers. Here, the load-in pins 845 extend from the lower chamber member210 to engage corresponding apertures (not shown) in the upper chambermember 205. The lead-in pins 845 are in the form of upstanding membersthat each terminate in a respective frustoconical section that functionsas a guide surface.

The foregoing arrangement makes the reactor 800 particularly well-suitedfor automated workpiece loading and unloading by, for example, a robotictransfer mechanism or the like, particularly one in which the workpieceis directly inserted into the reactor without flipping of the workpiece.As evident from a comparison of FIGS. 14 and 15, the spacing between thelower surface of the workpiece and the interior chamber wall of thelower chamber member 210 varies depending on whether the reactor 800 isin an open or closed state. When in the open state, the lower surface ofthe workpiece is spaced from the interior chamber wall of the lowerchamber member 210 by a distance, x1, that provides sufficient clearancefor operation of, for example, a workpiece transfer arm of a robotictransfer mechanism. When in the closed processing state, the lowersurface of the workpiece is spaced from the interior chamber wall of thelower chamber member 210 by a distance, x2, that is less than thedistance, x1. The distance, x2, in the disclosed embodiment correspondsto the spacing that is desired during workpiece processing operations.

One embodiment of the biasing member 815 is illustrated in FIG. 16. Asshown, the biasing member 815 is comprised of a plurality of leafsprings 835 that extend radially from a central hub portion 850 topositions in which they contact the underside of respective workpiecesupport members 810. A further plurality of radial members 855 extendfrom the hub 850 to positions in which they contact the underside ofrespective lead-in pins 845. Unlike the leaf springs 835, the furtherplurality of radial members 855 are not necessarily designed to flex asthe upper and lower chamber members 210 and 205 move toward theprocessing position. The biasing member 825 may be formed from a polymermaterial or the like which is resistant to the chemistry used in theprocessing environment. When formed from such a material, the workpiecesupport members 810 and lead-in pins 845 may be formed integral withtheir respective leaf springs 835 and radial members 855.

In the illustrated embodiment, the central hub portion 850 includes acentral aperture 900 that accommodates a securement 905 which connectsthe biasing member 815 to the underside of the lower chamber member 210.With reference to FIGS. 14 and 15, the securement 905 can be formed toprovide the processing fluid inlet through the lower chamber member 210.When the securement 905 is formed in this manner, the reactor 800 isprovided with a quick and easy manner of providing different inletconfigurations for different processes.

On occasion, it may be desirable to remove the reactor 800 from headportion 860. For example, the reactor 800 may be removed for service orfor replacement with a reactor that is designed for executing otherprocesses, or processing other workpiece types.

As shown in FIG. 14, the reactor 800 and the head portion 860 areengaged at a connection hub assembly 865 which allows the reactor 800 tobe easily connected to and disconnected from the head portion 860. Inembodiment illustrated in FIG. 15, the connection hub assembly 865 iscomprised of a head connection hub 870 that is fixed to the processinghead portion 860, and a reactor connection hub 875 that is fixed to thereactor 800. The connection hubs 870 and 875 are secured to one anotherduring normal operation by, for example, a threaded joint 880. A setscrew 885 extends through the head connection hub 870 and may be rotatedto engage a surface of or corresponding aperture in the reactorconnection hub 875 to thereby prevents the connection hubs 870 and 875from unscrewing.

When removal of the reactor 800 is desired, the reactor is rotated toalign set screw 885 with a corresponding channel sleeve 890 that isfixed to the head portion 860. The channel sleeve 890 is constructed toallow a user to extend a tool therethrough to engage the set screw 885.The set screw is then turned to raise it until it engages and secureswith a screw head block 895. Once secured in this manner, the headconnection hub 870 is rotationally locked with the head portion 860thereby allowing the reactor 800 and corresponding reactor connectionhub 875 to be unscrewed from the head connection hub 870 to remove thereactor.

In accordance with a still further feature of the reactor 800, astiffening member 910 formed, for example, from aluminum is secured withthe upper chamber member 205. By increasing the stiffness of the upperand/or lower chamber members, higher rotating speeds may be used and,further, the flatness of the interior chamber walls during processingmay be increased.

Numerous substantial benefits flow from the use of the disclosed reactorconfigurations. Many of these benefits arise directly from the reducedfluid flow areas in the reactor chambers. Generally, there is a moreefficient use of the processing fluids since very little of the fluidsare wasted. Further, it is often easier to control the physicalparameters of the fluid flow, such as temperature, mass flow, etc.,using the reduced fluid flow areas of the reactor chambers. This givesrise to more consistent results and makes those results repeatable.

The foregoing constructions also give rise to the ability to performsequential processing of a single wafer using two or more processingfluids sequentially provided through a single inlet of the reactionchamber. Still further, the ability to concurrently provide differentfluids to the upper and lower surfaces of the wafer opens theopportunity to implement novel processing operations. For example, aprocessing fluid, such as HF liquid, may be supplied to a lower fluidinlet of the reaction chamber for processing the lower wafer surfacewhile an inert fluid, such as nitrogen gas, may be provided to the upperfluid inlet. As such, the HF liquid is allowed to react with the lowersurface of the wafer while the upper surface of the wafer is effectivelyisolated from HF reactions. Numerous other novel processes may also beimplemented.

Further, wafers may be rinsed and dried on an individual basis morequickly when compared to the drying of an individual wafer using any ofthe foregoing processes.

FIG. 17 illustrates one manner of controlling the provision ofrinsing/drying fluids that are supplied to the rinser/dryer of any ofthe foregoing embodiments. As illustrated, the fluid supply system,shown generally at 1800, includes a nitrogen gas supply 1805, an IPAsupply 1810, an IPA vaporizer 1815, a DI water supply 1820, optionalheating elements 1825, optional flowmeters 1830, optional flowregulators/temperature sensors 1835, and valve mechanism 1840. All ofthe various components of the system 1800 may be under the control of acontroller unit 845 having the appropriate software programming.

In operation of the rinser/dryer, the valve mechanism 1840 is connectedto supply DI water from supply 1820 to both the upper and lower inletsof the rinser/dryer chamber. As the water is supplied to the chamber,the wafer is spun at, for example, a rate of 200 RPM. This causes thewater to flow across each surface of the wafer under the action ofcentrifugal force. Once a sufficient amount of water has been suppliedto the chamber to rinse the wafer surfaces, valve mechanism 1840 isoperated to provide a drying fluid, preferably comprised of nitrogen andIPA vapor, to both the upper and lower inlets of the rinser/dryerchamber. Valve mechanism 1840 is preferably operated so that the frontof the drying fluid immediately follows the trailing end of the DIwater. As the drying fluid enters the chamber, centrifugal forceresulting from the spinning of the wafer drives the drying fluid acrossthe wafer surface and follows a meniscus across the wafer surface formedby the DI water. The IPA vapor assists in providing a drying of thesurface of the wafer at the edge of the meniscus. Drying of the wafermay be further enhanced by heating the DI water and/or the nitrogen/IPAvapor using heating elements 1825. The particular temperature at whichthese fluids are supplied may be controlled by the controller 1845.Similarly, flow regulators 1835 and flowmeters 1830 may be used bycontroller 1845 to regulate the flow of the DI water and/or thenitrogen/IPA vapor to the rinser/dryer chamber.

With some modifications, the foregoing reactor designs may be adapted toexecute several unique processes in which contact between themicroelectronic workpiece and one or more processing fluids iscontrolled and confined to selected areas of the workpiece. Oneembodiment of such a reactor design is shown in FIGS. 18-22.

With reference to FIGS. 18-22, there is shown a reactor 2100 forprocessing a microelectronic workpiece, such as a silicon wafer 55having an upper side 12, a lower side 14, and an outer, circularperimeter 16, in a micro-environment. For certain applications, theupper side 12 is the front side, which may be otherwise called thedevice side, and the lower side 14 is the back side, which may beotherwise called the non-device side. However, for other applications,the silicon wafer 55 is inverted.

Generally, except as disclosed herein, the reactor 2100 is similar tothe reactors illustrated and described above. However, as illustrated inthe drawings and described herein, the reactor 2100 is improved to bemore versatile in executing selected microelectronic fabricationprocesses.

The reactor 2100 has an upper chamber member or rotor that includes anupper or chamber wall 2120 and a lower chamber member or rotor thatincludes a lower chamber wall 2140. These walls 2120, 2140, are arrangedto open so as to permit a wafer 55 to be loaded into the reactor 2100for processing, by a loading and unloading mechanism (not shown) that,for example, may be in the form of a robot having an end effector. Thesewalls 2120, 2140, are arranged to close so as to define a capsule 2160supporting a wafer 55 in a processing position, between these walls2120, 2140.

The reactor 2100, which defines a rotation axis A, has a head 2200containing a rotor 2210, which mounts the upper chamber wall 2120, andmounting a motor 2220 for rotating the rotor 2210 and the upper andlower chamber walls 2120, 2140, when closed, around the axis A,conjointly with a wafer 55 supported in the processing position. Themotor 2220 is arranged to drive a sleeve 2222, which is supportedradially in the head 2200, by rolling-element bearings 2224. The head2200 is arranged to be raised for opening these walls 2120, 2140, and tobe lowered for closing these walls 2120, 2140.

The upper chamber wall 2120 has an inlet 2122 for processing fluids,which may be liquid, vaporous, or gaseous, and the lower chamber wall2140 has an inlet 2142 for such fluids, which for a given applicationmay be similar fluids or different fluids. The head 2200 mounts an uppernozzle 2210, which extends axially through the sleeve 2222 so as not tointerfere with the rotation of the sleeve 2222. The upper nozzle 2210directs streams of processing fluids downwardly through the inlet 2122of the upper chamber wall 2120.

The upper chamber wall 2120 includes an array of similar outlets 2124,which are spaced similarly at uniform angular spacings around thevertical axis A. In the disclosed embodiment, thirty-six such outlets2124 are employed. The outlets 2124 are spaced outwardly from thevertical axis A by just slightly less than the workpiece radius. Theoutlets 2124 are also spaced inwardly from the outer perimeter 16 of awafer 55 supported in the processing position by a much smaller radialdistance, such as a distance of approximately 1-5 mm.

When the upper and lower rotors are closed together, the chamber walls2120, 2140 define a micro-environment reactor 2160 the having an upperprocessing chamber 2126 that is defined by the upper chamber wall 2120and by a first generally planar surface of the supported wafer 55, and alower processing chamber 2146 that is defined by the lower chamber wall2140 and a second generally planar surface of the supported waferopposite the first side. The upper and lower processing chambers 2126,2146, are in fluid communication with each other in an annular region2130 beyond the outer perimeter 16 of the supported wafer 55 and aresealed by an annular, compressible seal (e.g. O-ring) 2132 bounding alower portion 2134 of the annular region 2130. The seal 2132 allowsprocessing fluids entering the lower inlet 2142 to remain undersufficient pressure to flow toward the outlets 2124.

As compared to reactors of the type disclosed in the previouslydescribed embodiments, the reactor 2100 is particularly suitable forexecuting a range of unique microfabrication processes. For example,reactor 2100 is particularly suited to execute a process that requirescomplete contact of a processing fluid at a first side of a workpieceand at only a perimeter margin portion of the second side thereof. Suchprocesses may be realized because processing fluids entering the inlet2142 of the lower chamber wall 2140 can act on the lower side 14 of asupported wafer 55, on the outer perimeter 16 of the supported wafer 55,and on an outer margin 18 of the upper side 12 of the supported wafer 55before reaching the outlets 2124, and because processing fluids enteringthe inlet 2122 of the upper chamber wall 2120 can act on the upper side12 of the supported wafer 55, except for the outer margin 18 of theupper side 12, before reaching the outlets 2124.

As a significant example of one such process, the reactor 2100 can beused with control of the respective pressures of processing fluidsentering the respective inlets 2122, 2142, to carry out a process inwhich a processing fluid is allowed to contact a first side of theworkpiece, the peripheral edge of the workpiece, and a peripheral regionof the opposite side of the workpiece. Such fluid flow/contact can alsobe viewed as a manner of excluding a processing fluid that is applied tothe opposite side from a peripheral region of that side. In accordancewith one embodiment of such a process, a thin film of material is etchedfrom the first side, peripheral edge of the workpiece, and peripheralregion of the opposite side of the workpiece.

In a more specific embodiment of such a process, the process mayemployed in a metallization process that is used to form amicroelectronic component and/or interconnect structures on asemiconductor wafer or the like. To this end, a thin film, such as theseed layer, is applied over a barrier layer on the front side and overat least a portion of the outer perimeter. After one or more interveningsteps, such as electroplating of a copper layer or the like thereover,an etchant capable of etching the electroplating material, thin filmmaterial, and/or the barrier layer material is caused to flowselectively over only an outer margin of the first side while beingconcurrently prevented from flowing over other radial interior portionsof the first side. Thus, one or more of the layers are removed from theouter margin of the first side while the layers remain intact at theportions of the first side that are disposed interior of the outermargin. If the etchant is driven over the opposite side and over theouter perimeter, as well as over the outer margin of the first side, theone or more layers are also removed from the outer perimeter of thewafer and, further, any contaminant that the etchant is capable ofremoving is stripped from the back side.

Based on the description of the foregoing process, it will be recognizedthat other layers and/or materials may be selectively etched, cleaned,deposited, protected, etc., based on selective contact of a processingfluid with the outer margin and/or opposing side of the workpiece. Forexample, oxide may be removed from the opposite side and outer margin ofthe first side of a workpiece through selective contact with an oxideetchant, such as hydrofluoric acid. Similarly, the oxide etchant may becontrolled in the reactor so that it contacts all of the front side ofthe workpiece except for the outer margin thereby leaving the oxide atthe outer margin intact. It will also be recognized that removal of theoutlets 2124 allows the reactor 2100 to be used for processes in whichselective outer margin inclusion or exclusion is unnecessary orotherwise undesirable.

As illustrated in FIGS. 19-20, additional structures may be incorporatedwith any of the foregoing reactors dependent on the particularprocess(es) the reactor is designed to implement and the automation, ifany, that will be used along with it. In accordance with one suchstructural addition, the lower chamber wall 2140 has an upper surface2144 shaped so as to define an annular sump 2146 around the inlet 2142.The sump 2146 is used to collect liquid byproducts and/or residualprocessing fluids supplied through the inlet 2142. If a liquid, forexample, strikes and drops from wafer 55, it is conducted toward theoutlet 2124 under the influence of centrifugal force as the reactor 100is rotated.

Another structural addition illustrated in connection with the reactor2100 relates to the lower nozzle design. As illustrated, the lowernozzle 2260, which is provided beneath the inlet 2142 of the lowerchamber wall 2140, includes two or more ports 2262, as shown in FIG. 19,for directing two or more streams of processing fluids upwardly throughthe inlet 2142. The ports 2262 are oriented so as to cause the directedstreams to converge approximately where the directed streams reach thelower surface of the wafer 55. The reactor 2100 also includes a purgingnozzle 2280, which is disposed at a side of the lower nozzle 2260, fordirecting a stream of purging gas, such as nitrogen, across the lowernozzle 2260.

Still further, the reactor 2100 may have a base 2300, which mounts thelower nozzle 2260 and the purging nozzle 2280 and which defines acoaxial, annular plenum 2320. The plenum 2320 has plural (e.g four)drains 2322 (one shown) each of which is equipped with a pneumaticallyactuated, poppet valve 2340 for opening and closing the drain 2322.These drains 2322 provide separate paths for conducting processingliquids of different types to appropriate systems (not shown) forstorage, disposal, or recirculation.

An annular skirt 2360 extends around and downwardly from the upperchamber wall 2120, above the plenum 2320, so as to be conjointlyrotatable with the upper chamber wall 2140. Each outlet 2124 is orientedso as to direct processing fluids exiting such outlet 2124 through fluidpassages 2124 against an inner surface 2362 of the annular skirt 2360.The inner surface 2362 is flared outwardly and downwardly, as shown, soas to cause processing fluids reaching the inner surface 2362 to flowoutwardly and downwardly toward the plenum 2320, under the influence ofcentrifugal force when the reactor is rotated. Thus, processing fluidstend to be swept through the plenum 2320, toward the drains 2322.

The rotor 2210 has a ribbed surface 2215 facing and closely spaced froma smooth lower surface of the head 2200, in an annular region 2204communicating with the plenum 2320. When the rotor 2210 rotates, theribbed surface 2215 tends to cause air in the annular region 2204 toswirl, so as to help to sweep processing fluids through the plenum 2320,toward the drains 2322.

The upper chamber wall 2120 has spacers 2128 that project downwardly toprevent the lifting of a supported wafer 55 from the processing positionand from touching the upper chamber wall 2120. The lower chamber wall2140 has spacers 2148 that project upwardly for spacing a supportedwafer 55 above the lower chamber wall 140 by a given distance, and posts2150 projecting upwardly beyond the outer perimeter 16 of a supportedwafer 55 for preventing the supported wafer 55 from shifting off centerfrom the vertical axis A.

Referring to FIGS. 24-26, the lower chamber wall 2140 may mount alifting mechanism 2400 for lifting a wafer 55 supported in theprocessing position to an elevated position. The lifting mechanism liftsthe wafer 55 to the elevated position when the head 2200 is raised abovethe base 2300 so as to open the upper and lower chamber walls 2120,2140. Lifting a supported wafer 55 to the elevated position facilitatesits being unloaded by a loading and unloading mechanism (not shown) suchas a robotic arm having an end effector.

The lifting mechanism 2400 includes an array of lifting levers 2420.Each lifting lever 2420 is mounted pivotably to the lower chamber wall2140 via a pivot pin 2422 extending from such lifting lever 2420 into asocket 2424 in the lower chamber wall 2140, so as to be pivotablebetween an operative position and an inoperative position. Each pivotinglever 2420 is arranged to be engaged by the upper chamber wall 2120 whenthe upper and lower chamber walls 2120, 2140, are closed, whereby suchpivoting lever 2420 is pivoted into the inoperative position. Eachlifting lever 2420 is biased, as described below, so as to pivot intothe operative position when not engaged by the upper chamber wall 2120.

Thus, each lifting lever 2420 is adapted to pivot from the operativeposition into the inoperative position as the upper and lower chamberwalls 2120, 2140, are closed, and is adapted to pivot from theinoperative position into the operative position as the upper and lowerchamber walls 2120, 2140, are opened. A pin 2424 on each lifting lever2420 extends beneath a wafer 55 supported in the processing position andlifts the wafer to the elevated position, when such lifting lever 2420is pivoted from the inoperative position into the operative position.

The lifting levers 2420 may be biased by an elastic member 2440 (e.g.O-ring) surrounding the lower chamber wall 2140 and engaging the liftinglevers 2420, via a hook 2425 depending from each lifting lever 2420. Oneach lifting lever 2420, the pin 2422 defines an axis, relative to whichthe pin 2426 and the hook 2425 are opposed diametrically to the eachother. The elastic member 2440 is maintained under comparatively highertension when the upper and lower chamber walls 2120, 2140, are closed,and under comparatively lower tension when the upper and lower chamberwalls 2120, 2140, are opened.

Referring momentarily to FIG. 20, the upper and lower chamber walls2120, 2140, may also be releasably clamped to each other when in theclosed state by a latching mechanism 2500. As shown in FIGS. 19, 20A and20B, the latching mechanism includes a latching ring 2520 that isretained by the lower chamber wall 2140 and that is adapted to engage acomplementary shaped recess 2540 disposed in the upper chamber wall2120. The latching ring 2520 is made from a resilient spring material(e.g polyvinylidine fluorid) with an array of inwardly stepped portions2350 which allow the latching ring 2520 to deform from an undeformedcondition in which the latching ring 2520 has a first diameter into adeformed condition in which the latching ring 2520 has a comparativelysmaller diameter. Such deformation occurs when the stepped portions 2530are subject to radial inward directed forces. Upon removal of theforces, the latching ring 2520 returns to the undeformed.

The latching mechanism 2500 further includes an array of latching cams2540, each associated with a respective one of the stepped portions2530. Each latching cam 2540 is adapted to apply radial forces to therespective stepped portions 2530.

As shown in FIG. 19, the latching mechanism 2500 further includes anactuating ring 2560, which is adapted to actuating the latching cams2540 as the actuating ring 2560 is raised and lowered within apredetermined limited range of movement. The actuating ring 2560 isadapted, when raised, to actuate the latching cams 2540, and, whenlowered, to deactuate the latching cams. Pneumatic lifters 2580 (e.g.three such devices) are adapted to raise and lower the actuating ring2560. When the actuating ring 2560 is raised, the upper and lowerchamber walls 2120, 2140, are released from each other so that the head2200 can be raised from the base 2300 for opening the upper and lowerchamber walls 2120, 2140, or lowered onto the base 2300 for closing theupper and lower chamber walls 2120, 2140.

As shown in FIG. 20A, pins 2562 (one shown) on the actuating ring 2560project upwardly and into apertures 2564 in an aligning ring 2570, whenthe actuating ring 2560 is raised. The aligning ring 2570 is joined to,and rotates with, the lower chamber wall 2140. The pins 2562 arewithdrawn from the apertures 2564 and clear the aligning ring 2570 whenthe actuating ring 2560 is lowered. When projecting into the respectiveapertures 2564, the pins 2562 align a wafer 55 that had been supportedin the processing position so as to facilitate unloading the wafer 55via a robotic system, as mentioned above.

FIGS. 27-30 show rotor edge configurations useful for processing anannular perimeter area, for carrying out process steps, as describedabove in connection with FIGS. 20-21.

Referring to FIGS. 27 and 28, in an alternative reactor embodiment 2600,an upper rotor 2602 has a top section 2606, joined to a side section2608. The top section 2606 is joined to or integral with an upper webplate 2610, which in turn is joined to a shaft, such as the shaft 260and drive motor described above.

A lower rotor 2604 has a vertical wall 2614 extending upwardly from abase section 2612. The vertical wall 2614 has an inner surface 2616 andan outer surface 2618. An o-ring groove 2620 in the outer surface 2618contains an o-ring 2622, sealing the lower rotor 2604 against the insidesurface 2624 of the side section 2608 of the upper rotor 2602, when therotors are engaged together. The reactor 26 is rotatably mounted withina head 2200, or other enclosure.

A wafer 55 or other workpiece is supported at its perimeter by lowerspacing members or pins 105 extending upwardly from the base section2612 of the lower rotor 2604, and by upper spacing members or pins 110extending downwardly from the top section 2606 of the upper rotor 2602.The end face or edge 58 of the wafer 55 is spaced slightly away from theinner surface 2616 of the vertical wall 2614. The pins 105 and 110 areof small diameter and have a minimum contact surface with the wafer 55.Accordingly, virtually the entire upper surface 57 and lower surface 59of the wafer 55 is spaced apart from the structure of the reactor 2600.

Referring momentarily to FIG. 28, the upper and lower rotors 2602 and2604 are substantially open, due to the web-like structure of therotors. The pins 105 and 110, are radially spaced apart around theperimeter of the rotors.

In use, a processing fluid is applied to the top surface 57 of the wafer55, preferably at a central area, as with the embodiments describedabove. The fluid 2630 flows radially outwardly over the top surface 57and into a reservoir 2650 formed by the upper and lower rotors 2602 and2604. Specifically, the reservoir 2650 is formed or defined on top bythe top section 2606, on the bottom by the base section 2612, and on theoutside by the inner surface 2616 of the vertical wall 2614. The insidesurface of the reservoir 2650, i.e., the surface closest to the spinaxis A, is open. Consequently, the reservoir 2650 is formed as athree-sided groove, having a top, bottom, and outside wall, but noinside wall.

In use, the upper and lower rotors are initially vertically spaced apartor separated. A wafer 55 or other workpiece is placed into the lowerrotor 2604, either manually, or via a robot. The wafer rests on thelower spacing members or pins 105. The upper and lower rotors are thenbrought together. As this occurs, the wafer 55 is supported or held inplace from above by the upper spacing member 110. Consequently, thewafer 55 is secured between the rotors. At the same time, the o-ringmakes sliding contact with, and seals against, the upper rotor 2602.

The reactor 2600 is then accelerated up to a process spin speed.Processing fluid is introduced onto the upper surface 57 of the wafer55. The fluid 2630 flows radially outwardly and into the reservoir 2650,via centrifugal force. Referring once again to FIG. 28, the pins 105 and110 do not significantly obstruct the flow of the fluid 2630 into thereservoir 2650, as the reservoir 2650 extends completelycircumferentially around the reactor 2600, while the pins occupy a verysmall area.

The reservoir 2650 fills with fluid 2630 running off of the wafer. Thefluid is forced radially outwardly via centrifugal force, and thus itremains in the reservoir, and does not flow out of the open innersurface of the reservoir (i.e., the open side facing the spin axis A).Typically, a small gap 2626 remains between the upper rotor 2602 and thelower rotor 2604. Fluid may flow through this gap, is stopped when itreaches the o-ring 2622. With the reservoir 2650 filled, as additionalfluid moves outwardly along the top surface 57 and into the reservoir,fluid is simultaneously displaced from the reservoir, as run-off 2632over the inside lip or edge 2615 of the base section 2612 of the lowerrotor 2604. The run-off 2632 runs down and then radially outwardly, andoff of the rotors. The head or enclosure 2200 captures or deflects therun-off 2632.

With the spin speed and supply rate of fluid held approximatelyconstant, a relatively sharply defined and consistent separation line2634 is formed on the lower surface 59 of the wafer 55. Consequently,the entire upper surface 57, the outside edge 58, and an outside annularperimeter area, on the lower surface 59 (extending inwardly from theedge 58 to the separation line 2634), are covered with the fluid 2630,and consequently, are processed. The width of the annular perimeter areaprocessed on the bottom surface 59, i.e., the dimension between the edge58 and the separation line 2634, typically ranges from about 1-5 mm, andis usually about 3 mm. The entire central area of the lower surface 59,is not processed, as it is not contacted by the fluid.

FIG. 29 discloses an alternative reactor design 2700 having an upperrotor 2702 and a lower rotor 2704. In contrast to the reactor 2600 shownin FIG. 27, the reactor 2700 in FIG. 29 has continuous disk orplate-like upper and lower rotors. Specifically, the upper rotor 2702includes a side section or leg 2708 joined perpendicularly to acontinuous round upper plate 2706. Similarly, the lower rotor 2704includes an upright leg 2710 attached perpendicularly to a round andgenerally continuous lower rotor plate or disk 2712. With the upper andlower rotors engaged together, the side section 2708 of the upper rotor2702 is sealed against the upright leg 2710 of the lower rotor 2704 viaan o-ring 2622 in an o-ring groove 2720 in the side section 2708.

In use, the wafer 55 is supported between the rotors on supports or pins105 and 110. The edge 58 of the wafer 55 is spaced slightly away fromthe inner surface 2716 of the side section 2708.

Processing fluid is introduced onto the top surface 57 of the wafer 55,while the reactor 2700 is spinning. The fluid flows radially outwardlyinto a reservoir 2750, similar to operation of the reactor 2600 asdescribed above. Fluid flowing through any gap 2726 between the upperand lower rotors is stopped by the o-ring 2622. A drain hole 2730 isprovided through the lower rotor 2704, at a location radially inwardlyfrom the edge 58, typically by about 3 mm. The fluid 2630 flows out ofthe hole 2730, with the fluid run-off 2732 flowing out along the bottomsurface of the lower rotor 2704, and then onto the head or enclosure2200. The id fluid flowing out of the hole 2730 forms a sharpcircumferential separation line 2734. Consequently, the annularperimeter area of the lower surface 59 of the wafer 55 is processed,while the remaining (e.g., 194 mm diameter area of a 200 mm wafer)remains unprocessed.

FIG. 30 shows yet another reactor embodiment 2800 having an upper rotor2802 with an upper central opening 2808. A lower rotor 2804 may eitherhave a web configuration, as shown in FIG. 28, or it may mechanicallyattach to the upper rotor 2802 via an attachment 2809. A flange 2810 onthe upper rotor 2802 seals against the lower rotor 2804 via an o-ring2622 in a groove 2820 in the lower rotor 2804. The wafer or otherworkpiece 55 is supported between the rotors on supports 105 and 110, asdescribed above. A drain hole 2830 extends through the upper rotor 2802,just inside the reservoir 2850 formed by the flange 2810 of the upperrotor 2802 and the lower rotor 2804.

In use, processing fluid 2630 is introduced onto the lower surface 59 ofthe wafer 55 at the center (on the axis A). Preferably, the fluid isintroduced via a nozzle 130 having multiple jets 132. The fluid 2630flows radially outwardly on the bottom surface 59 and fills thereservoir 2850. The fluid runs out from the drain hole 2830, creating aseparation line 2834, cleanly separating the processed outside annulararea of the upper surface 57 of the wafer 55, from the unprocessed innersurface. Purged gas is preferably introduced through the upper centralopening 2808 and exhausts out of the drain hole 2830. The purge gaskeeps the area above the top surface 57 free of fluid vapors. Purge gasmay also be used in the reactors 2600 and 2700.

In the embodiment shown in FIGS. 29 and 30, a single drain hole, ormultiple drain holes may be used. The reactors shown in FIGS. 27-30,except as described above in connection with FIGS. 27-30, operate (e.g.,in terms of their fluid delivery, rotor spin, rotor design, etc.) in thesame way as the reactors shown in FIGS. 1, 2, 14 and 18.

The present invention has been illustrated with respect to a wafer.However, it will be recognized that the present invention has a widerrange of applicability. By way of example, the present invention isapplicable in the processing of disks and heads, flat panel displays,microelectronic masks, and other devices requiring effective andcontrolled wet processing.

Numerous modifications may be made to the foregoing system withoutdeparting from the basic teachings thereof. Although the presentinvention has been described in substantial detail with reference to oneor more specific embodiments, those of skill in the art will recognizethat changes may be made thereto without departing from the scope andspirit of the inventions. The inventions therefore, should not belimited, except by the following claims, and their equivalents.

What is claimed is:
 1. A method for processing a workpiece, comprisingthe steps of: spinning the workpiece; applying a processing fluid to afirst side of the workpiece; allowing the processing fluid to flowoutwardly over the first side of the workpiece, via centrifugal forcegenerated by the spinning; collecting the processing fluid at theperimeter of the workpiece, so that the processing fluid flows onto anouter annular area of a second side of the workpiece.
 2. The method ofclaim 1 wherein the workpiece spins about a vertical axis, and the firstside of the workpiece is the top side.
 3. The method of claim 1 whereinthe workpiece spins about a vertical axis, and the first side of theworkpiece is the bottom side.
 4. The method of claim 1 furthercomprising the step of supporting the workpiece on spacing pins within areactor, so that substantially the entire first surface of the workpieceis exposed to the fluid.
 5. The method of claim 1 further comprising thestep of confining the fluid within an annular chamber around the outerannular area on the second surface.
 6. The method of claim 5 furthercomprising the step of cutting off the introduction of fluid to thefirst surface of the workpiece, and continuing to spin the article. 7.The method of claim 1 further comprising the step of creating an annularreservoir of fluid at the perimeter of the workpiece.
 8. The method ofclaim 1 further comprising the step of confining the workpiece betweenan upper rotor and a lower rotor, and spinning the workpiece by spinningthe rotors.
 9. The method of claim 8 further comprising the step ofsupporting the workpiece on spacing members between the upper and lowerrotors, with the first side and the second side of the workpiece spacedapart from the upper rotor, and the lower rotor, respectively, by adimension D.
 10. The method of claim 9 wherein D equals 0.5-1.2 mm. 11.The method of claim 9 further comprising the step of sealing the upperrotor against the lower rotor.
 12. The method of claim 1 furthercomprising the step of applying the fluid at a central area of theworkpiece.
 13. The method of claim 1 further comprising the step ofapplying the fluid at a specified flow rate to create an annularreservoir at the perimeter of the workpiece, and then draining fluid outof the reservoir at the specified flow rate, to maintain the fluid inthe reservoir at a constant volume.
 14. The method of claim 1 furthercomprising the step of maintaining the fluid on a fixed annular area ofthe second surface of the workpiece.
 15. A method for processing asemiconductor article, comprising the steps of: supporting a firstsurface of the article on a plurality of first spacing pins on a firstrotor; moving an first rotor and the second rotor towards each other;supporting a second surface of the article on a plurality of secondspacing pins on the second rotor; sealing the second rotor against thefirst rotor, to form an annular reservoir chamber between them, with thearticle having a perimeter area extending into the annular reservoirchamber; rotating the first and second rotors together; introducing aprocessing fluid onto the first surface of the article; allowing thefluid to flow radially outwardly over the first surface via centrifugalforce; collecting the fluid in the annular reservoir chamber, so thatthe chamber fills with fluid; and withdrawing fluid from the chamber viaan opening overlying the perimeter area.
 16. The method of claim 15further comprising the step of introducing fluid and withdrawing fluidat the same volumetric flow rate, after the reservoir chamber is filled.17. A method of processing an annular edge area of an article,comprising the steps of: positioning the annular edge area of thearticle within an annular reservoir chamber; spinning the annularreservoir chamber and the article; filling the chamber with a processingfluid; and maintaining the fluid within the annular reservoir chamber,so that the fluid contacts only the annular edge area of the article.18. A method for processing a workpiece comprising the steps of:spinning the workpiece; introducing a process liquid to a perimeter areaof the workpiece; and confining the process liquid to the perimeter areaof the workpiece.
 19. The method of claim 18 where the process liquid isconfined by spinning an annular chamber with the workpiece, and with theannular chamber enclosing the perimeter area of the workpiece.
 20. Themethod of claim 18 where the process liquid is introduced to theperimeter area by moving radially outwardly to the perimeter area viacentrifugal force.
 21. The method of claim 20 where the process liquidis applied to a central area of the workpiece.
 22. The method of claim21 where the workpiece comprises a round semiconductor wafer.
 23. Themethod of claim 18 where the workpiece has a top surface and a bottomsurface, further including the step of excluding the process from acentral area of at least one of the top and bottom surfaces, viacentrifugal force.
 24. The method of claim 18 where the workpiece hascircular edge, and the perimeter area extends from 1-5 mm inwardly fromthe edge towards a center point of the workpiece.
 25. The method ofclaim 18 where the spinning is performed about vertical axis.
 26. Themethod of claim 18 further comprising the step of introducing a purgegas to the workpiece.
 27. A method of processing a workpiece having atop surface, and a bottom surface, and a circular edge, comprising thesteps of: placing the workpiece into a first rotor; engaging a secondrotor with the first rotor, with the first and second rotors togetherforming an annular chamber enclosing at least a perimeter area of theworkpiece, adjacent to the circular edge of the workpiece; spinning theengaged first and second rotors; filling the annular chambersufficiently with a liquid so that the liquid contacts the perimeterarea of the workpiece, on the top surface and on the bottom surface; andcontaining the liquid within the annular chamber.
 28. The method ofclaim 27 further comprising the step of supplying liquid into theannular chamber, and draining liquid out of the annular chamber, whilethe annular chamber is spinning.
 29. The method of claim 28 furthercomprising the steps of holding the spin speed constant for selectedamount of time, and maintaining a constant volume of liquid in theannular chamber, to form a separation line on at least one of the topand bottom surfaces.
 30. The method of claim 27 wherein the workpiece isround.
 31. The method of claim 27 wherein the first and second chamberentirely enclose the workpiece.
 32. The method of claim 27 furtherincluding the step of supporting the workpiece spaced apart from thefirst rotor and the second rotor.
 33. The method of claim 27 where inthe first and second rotors have first and second chamber walls,respectively, and with first and second chamber walls spaced apart byfrom 1.5-3.6 mm.
 34. The method of claim 27 further including the stepof sealing the second rotor against the first rotor.
 35. The method ofclaim 27 where the annular chamber is filled by applying liquid to thetop surface of the workpiece adjacent a center area of the workpiece andmoving the liquid radially outwardly over the top surface and into theannular chamber, via centrifugal force.
 36. A method for processing aworkpiece, comprising the steps of: spinning the workpiece; applying afirst fluid to a first side of the workpiece; applying a second fluid toa second side of the workpiece; allowing the first and second fluids toflow outwardly over the first and second sides of the workpiece,respectively, via centrifugal force generated by the spinning; andcontaining the first and second fluids at the perimeter of theworkpiece.
 37. The method of claim 36 wherein the perimeter of theworkpiece is surrounded by an annular chamber, and wherein the first andsecond fluids are kept in the annular chamber by centrifugal force. 38.The method of claim 36 wherein the first fluid comprises an etchant andthe second fluid comprises an inert fluid.